based on my experience, it's indeed better to hire a personal driver through someone's recommendation.
I started my course of the driving lesson with some private instructor. He was a middle age old man, and i think he had a nasty temper, because he was yelling at me at all my mistakes. So it made my driving lesson stressful. And i don't really know what i'm learning either... so at the end of he 4th lesson. I decided to join my friend at the driving centre. Well, at least all my experience are good with the instructor there. They are patient and they tend to drill your weakness, and also forgive your mistake. And almost everything was a breeze.... most instructors are also friendly. And i got my license on the 1st attempt.
But still there are also people i know enjoyed the private instructor.